Breaking change: Remove MutableRepeatedFieldRef::Reserve() (reflect…

…ion)

An upcoming performance improvement in RepeatedPtrField is incompatible with this API. The improvement is projected to accelerate repeated access to the elements of `RepeatedPtrField`, in particular and especially sequential access.

PA: https://protobuf.dev/news/2024-12-13/
PiperOrigin-RevId: 707309375

common/values/parsed_map_field_value.cc

@@ -165,6 +165,7 @@ ParsedMapFieldValue ParsedMapFieldValue::Clone(Allocator<> allocator) const {
   auto cloned_field =
       cloned->GetReflection()->GetMutableRepeatedFieldRef<google::protobuf::Message>(
           cel::to_address(cloned), field_);
+  cloned_field.Reserve(field.size());
   cloned_field.CopyFrom(field);
   return ParsedMapFieldValue(std::move(cloned), field_);
 }

common/values/parsed_repeated_field_value.cc

@@ -160,6 +160,7 @@ ParsedRepeatedFieldValue ParsedRepeatedFieldValue::Clone(
   auto cloned_field =
       cloned->GetReflection()->GetMutableRepeatedFieldRef<google::protobuf::Message>(
           cel::to_address(cloned), field_);
+  cloned_field.Reserve(field.size());
   cloned_field.CopyFrom(field);
   return ParsedRepeatedFieldValue(std::move(cloned), field_);
 }

internal/json.cc

@@ -806,6 +806,7 @@ class MessageToJsonState {
     if (size == 0) {
       return absl::OkStatus();
     }
+    ReserveValues(result, size);
     CEL_ASSIGN_OR_RETURN(const auto to_value, GetRepeatedFieldToValue(field));
     for (int index = 0; index < size; ++index) {
       CEL_RETURN_IF_ERROR((this->*to_value)(reflection, message, field, index,
@@ -994,6 +995,9 @@ class MessageToJsonState {
   virtual absl::Nonnull<google::protobuf::MessageLite*> MutableStructValue(
       absl::Nonnull<google::protobuf::MessageLite*> message) const = 0;
 
+  virtual void ReserveValues(absl::Nonnull<google::protobuf::MessageLite*> message,
+                             int capacity) const = 0;
+
   virtual absl::Nonnull<google::protobuf::MessageLite*> AddValues(
       absl::Nonnull<google::protobuf::MessageLite*> message) const = 0;
 
@@ -1072,6 +1076,13 @@ class GeneratedMessageToJsonState final : public MessageToJsonState {
         google::protobuf::DownCastMessage<google::protobuf::Value>(message));
   }
 
+  void ReserveValues(absl::Nonnull<google::protobuf::MessageLite*> message,
+                     int capacity) const override {
+    ListValueReflection::ReserveValues(
+        google::protobuf::DownCastMessage<google::protobuf::ListValue>(message),
+        capacity);
+  }
+
   absl::Nonnull<google::protobuf::MessageLite*> AddValues(
       absl::Nonnull<google::protobuf::MessageLite*> message) const override {
     return ListValueReflection::AddValues(
@@ -1152,6 +1163,12 @@ class DynamicMessageToJsonState final : public MessageToJsonState {
         google::protobuf::DownCastMessage<google::protobuf::Message>(message));
   }
 
+  void ReserveValues(absl::Nonnull<google::protobuf::MessageLite*> message,
+                     int capacity) const override {
+    reflection_.ListValue().ReserveValues(
+        google::protobuf::DownCastMessage<google::protobuf::Message>(message), capacity);
+  }
+
   absl::Nonnull<google::protobuf::MessageLite*> AddValues(
       absl::Nonnull<google::protobuf::MessageLite*> message) const override {
     return reflection_.ListValue().AddValues(
@@ -2155,6 +2172,9 @@ class JsonMutator {
   virtual absl::Nonnull<google::protobuf::MessageLite*> MutableListValue(
       absl::Nonnull<google::protobuf::MessageLite*> message) const = 0;
 
+  virtual void ReserveValues(absl::Nonnull<google::protobuf::MessageLite*> message,
+                             int capacity) const = 0;
+
   virtual absl::Nonnull<google::protobuf::MessageLite*> AddValues(
       absl::Nonnull<google::protobuf::MessageLite*> message) const = 0;
 
@@ -2203,6 +2223,13 @@ class GeneratedJsonMutator final : public JsonMutator {
         google::protobuf::DownCastMessage<google::protobuf::Value>(message));
   }
 
+  void ReserveValues(absl::Nonnull<google::protobuf::MessageLite*> message,
+                     int capacity) const override {
+    ListValueReflection::ReserveValues(
+        google::protobuf::DownCastMessage<google::protobuf::ListValue>(message),
+        capacity);
+  }
+
   absl::Nonnull<google::protobuf::MessageLite*> AddValues(
       absl::Nonnull<google::protobuf::MessageLite*> message) const override {
     return ListValueReflection::AddValues(
@@ -2285,6 +2312,12 @@ class DynamicJsonMutator final : public JsonMutator {
         google::protobuf::DownCastMessage<google::protobuf::Message>(message));
   }
 
+  void ReserveValues(absl::Nonnull<google::protobuf::MessageLite*> message,
+                     int capacity) const override {
+    list_value_reflection_.ReserveValues(
+        google::protobuf::DownCastMessage<google::protobuf::Message>(message), capacity);
+  }
+
   absl::Nonnull<google::protobuf::MessageLite*> AddValues(
       absl::Nonnull<google::protobuf::MessageLite*> message) const override {
     return list_value_reflection_.AddValues(
@@ -2346,6 +2379,7 @@ class NativeJsonToProtoJsonState {
 
   absl::Status ToProtoJsonList(const JsonArray& json,
                                absl::Nonnull<google::protobuf::MessageLite*> proto) {
+    mutator_->ReserveValues(proto, static_cast<int>(json.size()));
     for (const auto& element : json) {
       CEL_RETURN_IF_ERROR(ToProtoJson(element, mutator_->AddValues(proto)));
     }

internal/well_known_types.cc

@@ -1534,6 +1534,15 @@ absl::Nonnull<google::protobuf::Message*> ListValueReflection::AddValues(
   return message->GetReflection()->AddMessage(message, values_field_);
 }
 
+void ListValueReflection::ReserveValues(absl::Nonnull<google::protobuf::Message*> message,
+                                        int capacity) const {
+  ABSL_DCHECK(IsInitialized());
+  ABSL_DCHECK_EQ(message->GetDescriptor(), descriptor_);
+  if (capacity > 0) {
+    MutableValues(message).Reserve(capacity);
+  }
+}
+
 absl::StatusOr<ListValueReflection> GetListValueReflection(
     absl::Nonnull<const Descriptor*> descriptor) {
   ListValueReflection reflection;

internal/well_known_types.h

@@ -1066,6 +1066,13 @@ class ListValueReflection final {
     return message->add_values();
   }
 
+  static void ReserveValues(absl::Nonnull<GeneratedMessageType*> message,
+                            int capacity) {
+    if (capacity > 0) {
+      message->mutable_values()->Reserve(capacity);
+    }
+  }
+
   absl::Status Initialize(absl::Nonnull<const google::protobuf::DescriptorPool*> pool);
 
   absl::Status Initialize(absl::Nonnull<const google::protobuf::Descriptor*> descriptor);
@@ -1103,6 +1110,9 @@ class ListValueReflection final {
   absl::Nonnull<google::protobuf::Message*> AddValues(
       absl::Nonnull<google::protobuf::Message*> message) const;
 
+  void ReserveValues(absl::Nonnull<google::protobuf::Message*> message,
+                     int capacity) const;
+
  private:
   absl::Nullable<const google::protobuf::Descriptor*> descriptor_ = nullptr;
   absl::Nullable<const google::protobuf::FieldDescriptor*> values_field_ = nullptr;